Bellows R A, Short R E, Staigmiller R B
USDA-ARS, Miles City, MT 59301.
J Anim Sci. 1994 Jul;72(7):1667-74. doi: 10.2527/1994.7271667x.
The study involved 44 primiparous, 2-yr-old heifers and 74 multiparous cows, 3 or 4 yr old, bred to a single Charolais bull. Variables were dam age (heifer, H; or cow, C), restricted (RE) or forced (FE) exercise for the last 90 d precalving, and natural (NP) or induced (IP) parturition. The RE dams were held in drylots; FE dams were on range until d 260 to 267 and walked 3.2 km/d for feed and water. Dams with IP received 10 mg of flumethazone on d 269 of gestation. Diets for FE and RE dams contained the same hay and grain, but FE dams were fed in amounts projected to give weight changes approximating those of RE dams. All dams were calved in drylots; thereafter, all pairs were maintained together on pasture to the end of the study. Exercise did not affect dystocia score or incidence, increased feed requirement 31% (P < .01), and gave a 14.8% higher (P < .05) pregnancy rate in the subsequent 45-d breeding season. We hypothesize the increased pregnancy may have resulted from a feed-endocrine effect related to body weight gain, body composition-metabolic changes, or subsequent higher feed intake.(ABSTRACT TRUNCATED AT 250 WORDS)
该研究涉及44头初产、2岁的小母牛和74头经产母牛，年龄为3或4岁，均与同一头夏洛来公牛配种。变量包括母畜年龄（小母牛，H；或母牛，C）、产犊前最后90天的限制运动（RE）或强制运动（FE），以及自然分娩（NP）或诱导分娩（IP）。限制运动组的母畜饲养在干栏式畜舍；强制运动组的母畜在第260至267天放牧，每天步行3.2公里觅食和饮水。诱导分娩的母畜在妊娠第269天接受10毫克氟甲噻嗪。强制运动组和限制运动组母畜的日粮含有相同的干草和谷物，但强制运动组母畜的饲喂量按预计体重变化与限制运动组母畜相近来投喂。所有母畜均在干栏式畜舍产犊；此后，所有母牛犊在整个研究期间一直共同饲养在牧场。运动并未影响难产评分或发生率，但使采食量增加了31%（P <.01），并使随后45天的繁殖季节妊娠率提高了14.8%（P <.05）。我们推测妊娠率增加可能是由于与体重增加、身体组成代谢变化或随后较高采食量相关的饲料 - 内分泌效应。（摘要截断于250字）
